Numerous types of rivets are known in the art. Blind rivets are distinguished in that the force required to set the blind rivet is not applied by force-absorbing stirrups on either side of a part to be riveted, but the head and foot of the rivet are pressed together by pulling on a mandrel passing through the interior of the blind rivet, the head being held at the part and the foot pulled towards the head by means of the mandrel.
The advantage of the blind rivet consists in that access to only one side of the work is required. Various “designs” have been developed for self-drilling blind rivets, but the creation of self-piercing blind rivets has not been considered, since the necessary deformability of the shank does not permit exertion of a piercing force.
A disadvantage of the blind rivet consists in that holes must be drilled or punched in the work in order to set the blind rivet. This is difficult especially when two parts are to be connected to each other, the parts not being movable relative to each other. Production of the holes in conjunction with orientation of the parts sometimes presents difficulties, so that the drilling and the setting of the rivet must take place in a fixed relative position of the parts. Even in the case of the self-drilling blind rivets, this problem arises, since during the drilling, two parts to be connected to each other may exhibit a small interval, and upon setting of the rivet, the two parts are shifted towards each other, so that owing to the shearing stresses, quality of the riveted connection is compromised. Besides, in the case of self-drilling blind rivets, chips are produced, which may damage the surfaces.
On the other hand, however, self-piercing rivets are known, as well as self-piercing nuts and bolts. In their case, the problem of finding a hole, or of displacement of the parts relative to each other, does not arise. A disadvantage of self-piercing nuts is that only comparatively small tensions and torques can be thus absorbed, since the nuts can be freed from the work with comparative ease. Furthermore, these rivets and nuts are usually processed in stationary installations, rendering this operation comparatively inflexible vis-à-vis changes of position.
The object of the present invention, then, is to specify a rivet element and a device, a die suited to the purpose, and a process for setting said rivet element, and/or a riveted connection and an employment of said riveted connection, whereby the disadvantages described are to be overcome. Furthermore, a fundamentally novel concept of a rivet element, a device and a process for setting a rivet element, for a riveted connection, and for an employment of said riveted connection, are to be specified.